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3 years ago

A runner runs a distance of 450 metres in a time of 50 seconds. What is his average speed?

Mathematics

1 answer:

vekshin13 years ago

4 0

Answer:

0.279 miles / 0.449 km

Step-by-step explanation:

convert the meters into miles/kilometers to get your answer

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What is the product of a+3 and −2a2+15a+6b2?

Lady bird [3.3K]

Answer:

c. 2a3+9a2+45a+6ab2+18b2

Step-by-step explanation:

(a+3) + (−2a2+15a+6b2)

Using distributed p. with and a and 3

a(−2a2) + a(15a) +a(6b2) and 3(−2a2) + 3(15a) + 3(6b2)

= -−2a3 + 15a2 + 6ab2 = -6a2 + 45a + 18b2

Now add like terms and put in standard form.

15a2+(-6a2) = 9a2

And equals

-2a3 + 9a2+45a+6ab2+18b2

Trust me I took the test and got 100%

Your welcome,

7 0

3 years ago

Read 2 more answers

10.

Kay [80]

Answer:

$\frac{(82)(2.4)^2}{104.139} \leq \sigma^2 \leq \frac{(82)(2.4)^2}{62.132}$

$4.535 \leq \sigma^2 \leq 7.602$

Now we just take square root on both sides of the interval and we got:

$2.2 \leq \sigma \leq 2.8$

And the best option would be:

A. 2.2 < σ < 2.8

Step-by-step explanation:

Information provided

$\bar X=32.1$ represent the sample mean

$\mu$ population mean

s=2.4 represent the sample standard deviation

n=83 represent the sample size

Confidence interval

The confidence interval for the population variance is given by the following formula:

$\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma^2 \leq \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}$

The degrees of freedom are given by:

$df=n-1=83-1=82$

The Confidence is given by 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , the critical values for this case are:

$\chi^2_{\alpha/2}=62.132$

$\chi^2_{1- \alpha/2}=104.139$

And replacing into the formula for the interval we got:

$\frac{(82)(2.4)^2}{104.139} \leq \sigma^2 \leq \frac{(82)(2.4)^2}{62.132}$

$4.535 \leq \sigma^2 \leq 7.602$

Now we just take square root on both sides of the interval and we got:

$2.2 \leq \sigma \leq 2.8$

And the best option would be:

A. 2.2 < σ < 2.8

3 0

3 years ago

What is the sqaure root of 40?

Kobotan [32]

Answer:

6.32455532034 or just 6

Step-by-step explanation:

8 0

3 years ago

Read 2 more answers

What values of x and y satisfy the system of equations {3x+2y=14x=4y−2? infinitely many solutions (5011,1811) (1811,5011) no sol

irinina [24]

3x+2y=14x=4y-2

(x,y)=(1/4,11/8)

8 0

3 years ago

Write an expression for the phrase.

vitfil [10]

Answer:

9+k-17

Step-by-step explanation:

sum of 9 and k

9+k

minus 17

9+k-17

5 0

3 years ago